:root {
  --backgroundColor1: white;
  --backgroundColor2: #eeeeee;
  --textColor: black;
  --borderColor: black;
  --backgroundColor1-hover: black;
  --textColor-hover: white;
}

[data-subject="dark"] {
  --backgroundColor1: #111;
  --backgroundColor2: black;
  --textColor: white;
  --borderColor: white;
  --backgroundColor1-hover: white;
  --textColor-hover: black;
}

body {
  font-size: 1.5rem;
  font-family: KaiTi, STKaiti, FangSong, STFangSong;
  color: var(--textColor);
  overflow: hidden;
  background-color: var(--backgroundColor1);
}

.main-content {
  position: fixed;
  left: 0;
  top: 10%;
  width: 100%;
  height: 90%;
  background-color: var(--backgroundColor1);
}

.main-content a {
  color: blue;
}

.htmlDisplayArea {
  width: 100%;
  height: 100%;
  border: 0;
}

.overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  z-index: 999;
}

.header {
  background-color: var(--backgroundColor2);
  position: fixed;
  display: flex;
  justify-content: space-between;
  left: 0;
  top: 0;
  width: 100%;
  height: 10%;
  z-index: 998;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

.li {
  display: flex;
  justify-content: space-between;
}

.left-content,
.right-content {
  align-items: center;
  display: flex;
}

.menuButton,
.subjectButton {
  cursor: pointer;
}

.sidebar {
  position: fixed;
  top: 0;
  right: -21rem;
  width: 19rem;
  height: 100%;
  box-shadow: -3px 0 15px rgba(0, 0, 0, 1.0);
  z-index: 1000;
  background-color: var(--backgroundColor2);
  border-radius: 0.2rem;
  border-color: var(--borderColor);
  overflow: auto;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

.sidebar ul {
  list-style-type: none;
  padding-left: 0;
}

.sidebar li {
  cursor: pointer;
  line-height: 2.5rem;
}

.sidebar li:hover {
  background-color: var(--backgroundColor1-hover);
  color: var(--textColor-hover);
}

.closeButton {
  position: absolute;
  top: 0.9rem;
  right: 1rem;
  cursor: pointer;
}

.closeButton:hover {
  color: grey;
}

@media (max-width: 980px) {
  .sidebar li {
    font-size: 1.2rem;
  }
}

@media (max-width: 790px) {
  .sidebar li {
    font-size: 1.2rem;
  }
}